A clathrate compound has been known as one of molecular compounds that two or more compounds are bound through relatively weak interactions other than covalent bonds, represented by hydrogen bonds or van der Waals forces. The clathrate compound has a property to dissociate into the original individual constituent compounds by simple operations, and is expected to have applications to technological fields, such as selective separation of useful substances, chemical stabilization, nonvolatilization, prolongation of release and powderization, in recent years.
A variety of clathrate compounds have been reported (in patents such as Japanese Patents Laid-open Nos. Sho 61-53201, Sho 62-22701 and Hei 6-166646). Functionality of molecular compounds including clathrate compounds is decided by how individual constituent compounds assemble. Therefore, it is extremely important to control the assembling form of constituent compounds in order to produce molecular compounds.
A general method for producing molecular compounds represented by clathrate compounds is that either a host compound or a guest compound is dissolved in a solvent and a reaction is carried out in a solution. In a known method using a solvent, a molecular compound is not formed depending on the type of the solvent used, or an obtained product contains only the solvent without the guest compound or partly includes the solvent although containing the guest compound. It has been pointed out to be difficult to select conditions in some cases.
Different from the above-mentioned method, several methods have been proposed for producing molecular compounds by directly mixing a host compound with a guest compound without using a solvent. For example, Japanese Patent Laid-open No. Sho 63-35533 discloses methods that a powder host compound having a phenyl group and a hydroxyl group in a molecule and more than 12 carbons and a powder guest compound having a phenyl group and a carbonyl group in a molecule are pulverized separately and then mixed to react; that the said host compound is mixed with the afore-mentioned guest compound to pulverize for carrying out a reaction; and that the said host compound is mixed with the guest compound to react while pulverizing them. Methods of pulverizing and mixing in a mortar and shaking to mix by a shaker are described as actual mixing methods. Japanese Patent Laid-open No. Hei 1-213236 describes a process for the preparation of a clathrate compound in a way that a guest compound that is solid at an ordinary temperature is heated to melt, followed by an addition of a powder host compound capable of reacting with the said guest compound to form a clathrate compound. Meanwhile, kneaders and granulators have been generally used to mix food staff, to make tablets of agricultural chemicals, drugs and the like, or to modify or reinforce resins.
Every known process by a solid-solid reaction for the preparation of a molecular compound is at a small scale. Nobody has ever considered implementing the production of a molecular compound by a solid-solid reaction industrially at a large scale. Besides, no examples of applications of kneaders or granulators to solid-solid or solid-liquid reactions have been known so far. Molecular compounds with improved stability have been looked for when they are actually used as various products or materials for products.
It is an object of the present invention to provide industrial processes for the preparation of molecular compounds, particularly molecular compounds with excellent stability, by solid-solid or solid-liquid reactions.